Rishabh Ghimire has a parasitic twin attached to his chest. It’s sapping his strength and must be removed before it costs him his life.

This extraordinary film tracks his family’s journey from their mountain home in Nepal to a leading hospital the heart of LA, where Rishabh receives the operation his parents hope will save his life.

6 years ago Macey and Mackenzie hit the headlines – only the second ever known case of conjoined twins born with a triplet sister.

Today Macey, Mackenzie and Madeline Garrison are beautiful girls, but how are they managing life after separation, and what medical challenges lie ahead?

Rishabh was born in January 2009 with a parasitic twin attached to his abdomen.

A rare phenomenon in any part of the world. In his native Nepal the birth was so remarkable that Rishabh was celebrated in the local community as an 8-limbed God.

The boy’s family, however, worried about their son’s health and were delighted when Dr James Stein, of the Children’s Hospital of Los Angeles, came to examine him in a hospital in Kathmandu.

Dr Stein's examinations of Rishabh revealed both good news and bad news.

Dr Stein found that the smaller, less formed, twin had two arms, two legs and a torso, but could confirm that the parastic twin lacked a brain and internal organs.

A simple stethoscope check however revealed that Rishabh was already suffering from an irregular heartbeat from the strain of having to support his twin.

Separations are not usually performed before babies are six months old, as they are too weak to withstand such a complex major operation.

So great were Dr Stein's concerns over the psychological implications of being joined to another body, that he believed the separation operation should take place before Rishabh is able to remember his twin, so ideally before he reaches 12 months. Time is ticking.

Rishabh's mother tells Dr Stein how she's noticed that small wounds aern't healing and also of her son's growing reluctanct to eat.

These are worrying signs for Dr Stein who knows that failing to thrive is a sign there may be problems with Rishabh’s heart.

In this remarkable new special programme, the time for separation has come – taking place in Los Angeles,under the watchful eye of expert paediatric surgeon Dr Stein.

Will Rishabh's parents be able to take home the new healthy, happy, singleton baby boy that they long for?

Also featured in this episode is another remarkable case of Dr James Stein’s never before told: conjoined twins – 7 year old twin American girls, who – incredibly - have a twin sister. There is only one other known case in the world of conjoined twins with a fraternal triplet.

The triplet’s family faced an agonising decision several years ago of whether to separate their conjoined twins. Now, six years on they are back to visit their surgeon Dr Stein for him to hear how they are progressing.